Carburetor



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C. J. GRACE CARBURETOR Sapt 17,- 1935.

Filed NOV. 18, 1952 Patented Sept. 17, 1935 V UNITED STATES PATENT OFFICE Application November 18, 1932, Serial No. 643,250

a In Great Britain November 23, 1931 8 Claims.

This invention relates to carburetors for use with internal combustion engines, and has for its object to provide an improved carburetor of simple and satisfactory construction, wherein the fuel supplied to the engine is varied wholly or in 1 carburetor at present in common use and wherein a mixture throttle valve is located on the engine or suction side of the fuel orifices.

According to the present invention the normally provided manually controlled throttle valve in a carburetor of the above the throttle type is replaced by the combination of a throttle valve so constructed and arranged that the suction effect of the engine upon said valve gives a moment tending to open it, with control means for adjusting a stop member whereby the amount of throttle opening is limited.

In a preferred form of carburetor in accordance with the invention the movement of the throttle valve is utilized to control the effective area of one or more fuel supply orifices.

.The invention is generally applicable to anterior throttle carburetors, e. g. it is applicable to carburetors in which the throttle valve is not positioned on the engine side of the fuel orifice.

An object of the invention is to provide an improved construction of anterior throttle type of carburetor capable of controlling the feeding of fuel accurately in dependence upon the suction effect of the engine. Another object is to provide a valve of this character including a novel auxiliary or cut-off valve adapted to be closed automatically when the throttle opening is zero. Other objects will become apparent from a reading of the following description, the appended claims, and the accompanyingdrawing.

The invention is illustrated in the accompanying drawing, which shows one form of carburetor in accordance therewith.

' In the drawing, Figure 1 is a sectional elevation; Figure 2 is an elevation; Figure 3 an elevation taken at right angles to Figure 2; Figure 4 a sectional elevation taken at right angles to Figure 1 and showing the throttle valve fully open; Figure 6 a sectional elevation corresponding to Figure 4 and showing'the throttle valve closed;

and Figure 5 a sectional plan taken on the line XX of Figure 4.

Referring tothe drawing, the carburetor therein shown is provided with a throttle valve I mounted on a shaft 2 which is not diametrical so 5 that suction on the right hand side thereof (see Figure 6) will tend to open the said .valve as indlcated by the broken curved lines in Figure 6. Of course, where (as is illustrated) a circular throttle valve is employed, the clearance allowed 10 must be sufiicient to prevent the valve jamming against the inside of the pipe in which it works as it opens. In carburetors of ordinary size, such as would be employed for automobiles, the amount of clearance necessary will not be excessive, but if for any reason a close fitting valve is required, a rectangular shape of valve and pipe may be adopted. The amount of opening of the throttle valve is limited by the engagement of a pin 5 which moves with the throttle valve, with an adjustable valve stop member comprising the end of an arcuate slot 3 in 'a lever 4 which is loosely mounted to rock about the axis of the shaft 2 and which is controlled from the usual throttle pedal or handle (not shown) through any convenient mechanical linkage (not shown), so that as the lever 4 rotates about the axis of the valve shaft 2, the maximum possible throttle opening is altered. As will be seen, there is fixedly mounted on the shaft 2 a pair of levers I, one on either side 0 fthe body of the carburetor. One of the levers l carries the pin 5 and each lever is formed with or carries a lifting arm 8 which engages a slot in the appropriate side of the lower portion of'a hollow saddle member 9 which is mounted as shown upon the main body It! of the carburetor (see Figure 1). Adjustment weighs I I of horseshoe form are provided as required on the saddle member 9. It will be seen that the weight of the saddle member with the various parts attached 40 thereto applies a restoring force tending to close the throttle and thatwhen the throttle opens it is constrained to lift the saddle member and parts attached thereto. Carried from the top V of the saddle member 9 is a modulating pin I 3 4 which is clamped to the said top by a clamping nut I4 and is slidable through a central hole in' an insert member I5 screwed into the main body of the carburetor, the pin I3 passing through a petrol tight packing gland It as shown. Passing through a second packing gland H in the body It! is a needle valve I8 adapted to seat in the top of a channel way I9 formed in the body I0 which channel communicates through a pipe (not shown) with a petrol supply source, e. g. the

gravity tank of a motor car or a petrol pump thereof. It will be seen that when the valve l8 closes, petrol supply is cut off (see Figure 6). If desired, manually operable means (not shown) may be provided for closing the valve l8 irrespective of the position of the throttle valve as and when required. Such manual control means could be utilized to cut oil petrol supply (e. g. when a vehicle is coasting down a hill) and resupply petrol at any required time, substantially without lag. It is not necessary that the valve i8 be used for this purpose, though it is convenient to do so, for any valve in the petrol supply to the fuel orifice may be utilized for the purpose in question so long as that valve is in such position that the volume of fuel between it and the said orifice, and which must be consumed before the fuel supply at the orifice is cut off, is relatively small, e. g. where there is a float chamher a valve for the purpose now in question should be on the orifice side thereof. For the sake of brevity, a fuel supply valve for the purpose above set forth will be referred to in the claims as a direct acting fuel supply valve. Under the head of the valve 18 is a spring l8 which, when the saddle member 9 is lifted, holds the valve I8 off its seat, but when the said saddle member 9 comes to its lowest position (Figure 6) a second spring 20 carried thereby forces the valve l8 to close. The channel 19 communicates with a channel 2| which in turn leads to channels 22 through the insert I so that, assuming the needle valve iii to be open, petrol can flow down round the modulating pin i3. As will be apparent from the drawing, the effective orifice area for petrol depends upon the position of the pin I3, the lower end of which is tapered so that as the pin moves up and down it controls the effective orifice area. Air is admitted when the saddle member is lifted via the spaces 23 which are open to the atmosphere at their lower ends and along the paths indicated by the arrows in Figure 5, which is a sectional plan taken on the line XX of Figure 4, As will be seen the modulating pin passes through a member 24 which, for purposes of adjustment (or, if desired, for purposes of manual control), is movable in position. As shown, the member 24 is bored and tapped to receive a screw 25 which passes through a slot 26 in the main body I0, said slot being at an angle to the horizontal. Thus, by slacking back the screw 25 and moving it along the slot 26 the height of the member 24 within the body i0 may be adjusted, and when a desired adjustment has been found, the member 24 may be locked in position by tightening the screw 25. The adjustment may be made such that a so-called dribble-jet effect occurs; that is to say, the member 24 may be adjusted (once and for all) to so low a position that owing to the relatively large area left or air to flow, and owing to the relatively redbricted passage between the induction pipe and he fuel orifice, changes of suction in the induction pipe do not substantiallydirectly affect the rate of flow of fuel from the fuel orifice so that this rate of flow becomes dependent substantially only upon the position of the modulating pin. In these circumstances a dribble-jet effect is said to occur.

Where it is desired to provide for manual control of the member 24 (as distinct from adjustment, i. e. time to time adjustment thereof), the screw 25 is replaced by a pin whose outer end is connected by a Bowden cable or any other convenient device to a suitable control lever for mixthe needle valve 18 is closed. If desired, the

modulating pin may be so shaped and positioned that at zero throttle opening the effective orifice area is zero.

Obviously the functions of the needle valve I8 and modulating pin l3 may both be performed by the latter device, i. e. the valve 18 may be omitted and the pin I3 arranged to seal the petrol supply line at or just before zero throttle opening. The illustrated arrangement is, however, preferred and is believed to be both more reliable and practical.

It will be seen that if the restoring force upon the throttle be properly adjusted, the carburetor will function in such manner that good atomization is always obtained, while the effect known as choking, which is apt to occur in many known forms of carbuetor, if the throttle is suddenly opened to too great an extent for the engine speed existing at the time, will not occur since the throttle will automatically close to the extent 30;

necessary to compensate. It will further be seen that the carburetor is very small, simple and easily manufactured, while there is no necessity to fit a float chamber and associated float valve.

What I claim is:-

1. In combination in a carburetor of the socalled anterior throttle type, an unbalanced throttle valve exposed to engine suction and which replaces the balanced manually actuated throttle valve normally provided in known carburetors of the type referred to, control means for adjusting a stop member limiting the amount of opening of said unbalanced throttle valve, and means, including a saddle member arranged to be lifted by the unbalanced throttle valve upon opening thereof, actuated by said unbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve, said saddle member also actuating a normally open needle valve in the fuel supply so as to close said valve when said saddle member is in a position adjacent that corresponding to zero throttle opening.

2. In combinationina carburetor of the so-called anterior throttletype,an unbalanced throttle valve exposed to engine suction and which replaces the balanced manually actuated throttle valve normally provided in known carburetors of the type referred to, said throttle valve being pivoted about an axis so positioned that the area or said valve to one side of said axis is greater than that to the other, control means for adjusting a stop member limiting the amount of opening of said unbalanced throttle valve, and a modulating pin movably mounted in a fuel supply orifice and actuated by said unbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve, said means including a saddle member arranged to be lifted by the unbalanced throttle valve upon opening 7 thereof, said saddle member also actuating a normally open needle valve in the fuel supply so as to close said valve when said saddle member is in a position adjacent that corresponding to zero throttle opening.

3. In combination in a carburetor of the socalled anteriorthrottle type, an unbalanced throttle valve exposed to engine suction and which replaces the balanced manually actuated throttle valve normally provided in known carburetors of the type referred to, control means for adjusting a stop member limiting the amount of opening of said unbalanced throttle valve, and a modulating pin movably mounted in a fuel supply orifice and actuated by said unbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve, said modulating pin passing through an apertured member leading through the aperture thereof to the induction pipe portion of the carburetor and communicating with the atmosphere, said apertured member being adjustable in position towards or away from said orifice.

4. In combination in a carburetor of the socalled anterior throttle type, an unbalanced throttle valve exposed to engine suction and which replaces the balanced manually actuated throttle valve normally provided in known carburetors of the type referred to, control means for adjusting a stop member limiting the amount of opening of said unbalanced throttle valve, and a modulating pin movably mounted in a fuel supply orifice and actuated by said unbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve said modulating pin passing through an apertured member leading through the aperture thereof to the induction pipe portion of the'carburetor and communicating with the atmosphere, said apertured member being adjusted to a position relatively remote from said orifice whereby a so-called dribble-jet effect is obtained as herein set forth.

5. In a carburetor wherein the normally provided manually controlled throttle valve is replaced by a throttle valve so constructed and arranged that the suction effect of the engine upon said valve gives a moment tending to open it, the combination of an air throttle valve pivotally mounted about an axis which is not diametrical so that the suction eifect on said valve on the two sides of said axis is unbalanced, an adjustable stop member associated with said valve for limiting the degree of opening of said valve, a fuel orifice located so as always to be on the engine side of the air inlet determined by the throttle opening and at the same time in a position of high velocity air flow past said throttle valve, and means including a saddle member arranged to be lifted by the air throttle valve upon opening thereof actuated by said air throttle valve for controlling the effective area of the fuel orifice, the whole arrangement being such that the throttle valve is capable of being opened to such an extent as to offer substantially no resistance to air flow and without masking the fuel orifice.

6. In a carburetor wherein the normally provided manually controlled throttle valve is replaced by a throttle valve so constructed and arranged that the suction effect of the engine upon said valve gives a moment tending to open it, the combination of an air throttle valve pivotally mounted about an axis which is not diametrical so that the suction effect on said valve on the two sides of said axis is unbalanced, an adjustable stop member associated with said valve for limiting the degree of opening of said valve, a fuel orifice located so as always to be on the engine side of the air inlet determined by the throttle opening and at the same time in a position of high velocity air flow past said throttle valve, a modulating pin movably mounted in said fuel orifice and actuated by said imbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve, and a saddle member arranged to be lifted by the said air throttle valve upon opening thereof, the whole arrangement being such that the throttle valve is capable of being opened to such an extent as to offer substantially no resistance to air flow and without masking the fuel orifice.

7. In a carburetor wherein the normally provided manually controlled throttle valve is replaced by a throttle valve so constructed and arranged that the suction effect of the engine upon said valve gives a moment tending to open it, the combination of an air throttle valve pivotally mounted about an axis which is not diametrical so that the suction effect on said valve on the two sides of said axis is unbalanced, an adjustable stop member associated with said valve for limiting the degree of opening of said valve, a fuel orifice located so as always to be on the engine side of the air inlet determined by the throttle opening and at the same time in a position of h gh velocity air flow past said throttle valve, and means including a saddle member provided with adjustment weights and arranged to be lifted by the air throttle valve upon opening thereof actuated by said air throttle valve for controlling the effective area of the fuel orifice, the whole arrangement being such that the throttle valve is capable of being opened to such an extent as to offer substantially no resistance to air flow and without masking the fuel orifice.

8. In a carburetor wherein the normally provided manually controlled throttle valve is replaced by a throttle valve soconstructed and arranged that the suction effect of the engine upon said valve gives a moment tending to open it, the combination of an air throttle valve pivotally mounted about an axis which is not diametrical so that the suction effect on said valve on the two sides of said axis is unbalanced, an adjustable stop member associated with said valve for limiting the degree of opening of said valve, a fuel orifice located so as always to be on the engine side of the air inlet determined by the throttle opening and at the same time in a position of high velocity air flow past said throttle valve, a modulating pin movably mounted in said fuel orifice and actuated by said unbalanced throttle valve for regulating the supply of fuel in dependence upon the degree of opening of said valve, and a saddle member provided with adjustment weights and arranged to be lifted by the said air throttle valve upon opening thereof, the whole arrangement being such that the throttle valve is capable of being opened to such an extent as to offer substantially no resistance to air flow and without masking the fuel orifice.

CHARLES JEENS GRACE. 

